Melting and casting unit



T. H. FORDE Feb. l2, 1935.

AZ l w 0J 2 Patented Feb. 12, 1935 i UNITED STATES PATENToFFica MELTING AND CASTING UNIT Thomas mrerde, oakland, Calif., assigner to l Diascope Corporation Ltd., San Francisco, Calif., a corporation of California.

Application October 30, 1931, Serial No. 572,109 v 1 Claim. (Cl. 22-69.1)

The invention relates to a device for melting trix such as the, inlay-ring 9 maybe removably casting material and applying the same to the inserted with its open side 12 at'the top opening mold to eiect the casting operation. 13 ofthe section. The closure section 3, which An object ofthe invention is toprovide a device as previously stated is Harranged to-,be positioned of the character described by which the melting over the section 2, is formedon its under side v5 `of the casting material and the application therewith a cavity '14 which is designedr in the ,operativev oi to the mold may be effected without oxidization position of the closure to define 'with the fopen side of the material. 120i thering a heating chamber 16. Interposed Another object of the invention is to provide a between the opposing edges 17 and 18 of the seclO device of the character described in which the tions is arranged a gasket 19 preferably formed 10 means for effecting the melting of the casting of an asbestos composition and adapted to effect a material is combined with the means of holding seal between the sections. Attachment of the the mold for the application of said material sections together may be effected by any suitable thereto. means such as the clamp 2l.

l5 A further object is to provide a device of the The portion of the closure section dening the 15 character described wherein the mold to which cavity 14 is in the nature of a refractory linthe casting material is to be applied is arranged ing 22 which is preferably in the form of an to form a part of the heating chamber in which inverted hollow frustrum of a cone. Arranged the material is to be melted. in the walls of the lining 22 are a plurality of 2O A still further object is to provide a device of electric heating elements 23 designed to heat the 20 the character described which will have a pyromchamber on being energized, suitable conductor eter that may be controlled to indicate the temleads 24 extending through the walls of the secperature of the heating chamber at different tion for connecting the elements to a source of points therein. electric current.

25 The invention possesses other objects and fea- The melting and casting operation in the use 25 tures of advantage, some of which, with the foreof my device is arranged to be effected with the going, will be set forth in the following descripcasting material and mold exposed only to a nontion of the preferred form of the invention which oxidizing gas such as hydrogen or nitrogen and is illustrated in the drawing accompanying and for this reason means are provided which permit forming part of the specification. It is to be the air in the heating chamber and mold to be 30 understood, however, that variations in the showdisplaced by a charge of such gas. As here ing made by the said drawing and description may shown, suitable passages 26 and 27 are provided be adopted within the scope of the invention as in the walls of the cover section which respecset forth in the claim. tively serve as an inlet for the non-oxidizing gas The drawing is a front elevation View, partly to the chamber and as outlet for the air displaced 35 in section, of a unit embodying the features of my thereby, suitable check valves 28 and 29 being invention. associated with the inlet and outlet passages in In the present embodiment of the invention the order that the desired pressure of gas may be unit is particularly designed for use in the pracmaintained in the chamber. The operating tice of dentistry and in dental laboratories, and pressure in the chamber during the casting oper- 40 more especially in melting and casting gold in `ation is above atmospheric so that pressure will the forming of inlays. As here shown the unit be applied against the molten material to force in general comprises an inlay-ring supporting same through the pouring passage 31 of the ring section 2 which forms the base of the unit, a cloand into the mold, the ring as will be understood sure sectionwhich carries electric heating means being formed of a porous material whereby the 45 and is arranged to cover the supporting section gas may rind its way therethrough and out of and form with the ring therein a non-oxidizing the cavity 8 through a suitable opening 32 in the heating chamber, and a pyrometer 4 mounted on wall 6. In order that the inlay ring may form the closure section and designed to permit a reada proper seal for the chamber, the edge portions ing of the temperature in different parts of the of the open side of the ring are held in sealing 5`0 chamber. engagement with the gasket 19 by means of a More specifically the supporting section 2 as spring 33 interposed between the bottom of the illustrated in the drawing comprises a bottom side ring and the wall 6. By being thus held by said wall 6 and an annular vertical side wall '7 which spring, the ring, particularly the open side there- 50 together denne a cavity 8 in which a casting maof, is maintained in a predetermined elevated relation in the chamber regardless of the depth of the ring.

'I'he pyrometer 4 is preferably carried by the section 3 as a xed part thereof and as here shown extends thereabove in the form of a centrally disposed standard 34 carrying a. reading dial 36. Operatively associated with the pyrometer is a thermo-couple 37 here shown carried on the lowerY extremityof a. vertically adjustable stem 38. By any suitable means such as the arm 39 fixed tothe stem and accessible from the 45x-,` terior of the standard, the stem and consequently the thermo-couple 37, may be positioned at any height in the chamber whereby the temperature of the chamber directly at the casting material or any portion of the chamber thereabove may be readily and accurately indicated on the dial. Y

` lThe operation of the unit can now be readilyA understood. Assuming that ancinlay-ring has been inserted in the supportingV section with a piece of casting: materiaL set VVin the depression leading to the pouring passage 3l, the sections are properly secured together with the'ring set in sealed position. l The Yair may then be dis placed.with the nitrogen or other suitable gas, and the electric current turned on'to energize the elements. This condition is then maintained to raise the temperature in the chamber suilicient to readily melt the casting material. When the material is thus melted the gas pressure is increased above atmospheric Whereby under the inuence thereof the molten material will be forced into the mold to insure a perfect casting. It will thus be clear that at no time is the casiting material subject to oxidization during the melting or casting operation, Vand that as a result thereof the nal product will be entirely free of any objectionable impurities.

rI claim: c In a unit of the character described, a base member having a concavity for the reception of a porous casting matrix and being open at the top and bottom, an enclosure member having a refractory Vinner surface and arranged to t over said first memberto 1define with said matrix a heating chamber, a lsealing gasket interposed between said members, means securing said members together, means in the second member providing an inlet and exit for gases to "andfrom the chamber, electric` heating elements Vcarriedby the second member, a pyrometer on said second member including a thermo-couple adjustablyY positionable in the chamber, and means resiliently urging/'the matrix in engagement with said gasket.

THOMAS VI-I. FORDE. 

